The invention relates to the antenna systems, and more particularly to the incorporation of slip rings and brushes for an antenna of the system to facilitate an electrical connection to electrical components associated with the antenna while permitting rotational movement of the antenna, and while reducing the overall height of the system.
Any antenna that rotates about an azimuthal axis beyond 360xc2x0 of rotation requires some means for maintaining electrical contact between the electronic components associated with the antenna and those in the supporting structure on which the antenna is mounted. One form of maintaining such an electrical coupling is through the use of conventional slip rings and brushes. Slip rings and brushes can be used to supply power to the various electrical/electronic components of the antenna such as the azimuthal and elevation drive motors, which allow positioning of the antenna in accordance with desired azimuth and elevation angles. Other electronic components that require electrical power and/or electrical control signals are gyroscopes and encoders that help to control pointing of the antenna.
Typically, the above-described slip rings and brushes are mounted on a top surface of an antenna base plate. However, such an arrangement serves to increase the overall height of the antenna system. Also, for a system with a large base, this would necessitate that the brushes extend across the base to reach the slip rings. Such a design would inhibit the attachment of other components onto the base because they would interfere with the brush holders as they would rotate. On high speed moving platforms, such as jet aircraft, the additional drag caused by an externally mounted antenna system is of serious concern. The additional drag can significantly reduce fuel economy of the aircraft and thus lead to higher operating costs for the aircraft.
It is therefore of principal importance that an apparatus used for supporting an antenna and its associated components be formed such that the overall height of the antenna can be kept to a minimum to thereby avoid negatively impacting the performance and cost associated with using an externally mounted antenna on a high speed moving platform such as a jet aircraft.
The present invention is directed to an antenna system apparatus for supporting an antenna which allows 360xc2x0 rotational movement of the antenna, and which provides a significantly lower height that previously designed antenna support systems. The apparatus of the present invention makes use of a movable platform for mounting an antenna thereon, and a stationary platform mounted adjacent the movable platform. The antenna is mounted on an upper surface of the movable platform and at least one slip ring is formed on a lower surface of the movable platform. More preferably, a plurality of slip rings are formed on the lower surface of the movable platform.
At least one brush, and more preferably a plurality of brushes, are mounted on a support such that the brushes can be placed in physical contact with the slip rings. A motor operatively associated with the movable platform is used to drive the movable platform rotationally about the stationary platform. In a preferred embodiment, the stationary and movable platforms are disposed generally coplanar to one another and incorporate a bearing assembly therebetween for facilitating smooth rotational movement of the movable platform. This slip ring design is not limited to coplanar mounting plates or the bearings integrated into those plates.
It is a principal advantage of the present invention that the slip rings and brushes are disposed adjacent the lower surface of the movable platform. This allows the overall height of the apparatus to be minimized by allowing the various electrical and electronic components associated with the antenna to be mounted directly on the upper surface of the movable platform, rather than on other structure disposed above the upper surface, which is common with previous antenna systems. This in turn helps to reduce the drag created by the antenna system when it is mounted on an external surface of a high speed mobile platform.
In a preferred embodiment the apparatus of the present invention comprises a circular movable platform and an annular stationary platform. A bearing assembly is disposed between an outer edge surface of the circular movable platform and an inner edge surface of the annular stationary platform. The bearing assembly facilitates smooth rotational movement of the movable platform.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.